Sphygmomanometer.



L. P. BISHOP &: R. GRACE.

SPHYGMOMANOMETER.

APPLICATION FILED MABHIB, 1908.

915,329, Patented Mar. 16, 1909.

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I ntoz-i g PlQlj UNITED STATES PATENT OFFICE.

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Specification of Letters Patent.

Patented March 16, 1909.

Application filed March 18, 1908. Serial No. 421,911.

To all whom it may concern:

Be it known that we, LoUIs F. BISHOP and RALPH GRACE, citizens of the United States, residin at the city of New York, in the boroug of Manhattan and State of New York, have invented certain new and useful Improvements in Sphygmomanometers, of which the following is a nil, clear, and exact description.

Our invention relates to an instrument for determining the blood ressure of man and animals, and commonly lmown as the sphygmomanometer. The types of apparatus for this purpose which have been proposed and used heretofore, ordinarily make use of glass indicators containing mercury or a fluid which is dis laced by air pressure. Ordinarily a smal hand pump has been provided to secure an air pressure in the a paratus equivalent to the blood pressure to lie measured, and this air pressure is then determined by the mercury or other manometer. With such an ap aratus, the attention of the physician is istracted in two ways, first, by the'necessity of manipulating the pump, and second, by the pulsations in the ressure caused by the pump strokes. T e lastmentioned effect is articularly disturbing because the normal' b ood pulsations are made use of as the indicating means for the test,

- and it is important that they should not be confused with an mechanical pulsations of the apparatus. esides this, 1t is evident that t e glass a paratus is very fragile and cannot be packed away and carried in a small compass.

It is the purpose of our present invention t provide a simple apparatus in which th above objections are overcome.

With this object in view, we have devised an'apparatus which does not rely u on air pressure or the manipulation of a han pump and which is compact and portable, and made of soft rubber or flexible material throughout, so that it is not liable to breakage.

The invention consists in the features of construction and combinations particularly pointed out in the appended claims, reference eing made to the accompanying drawin and specification which set forth a preferred embodiment of the invention.

In the drawing, Figure 1 is a general view showing a complete sphygmomanometer embodyin the principles of our invention. Fig. 2 is a etail view partly in section, showing one of the parts. Fig. 3 is a detail view partly broken away, showing the cuff or bandage.

Referring to the drawing, in which like parts are designated by the same reference sign, 1 indicates a cuff or bandage designed to be applied to thearm or body of the patient, and comprising a vessel having a membranous wall which can be forced against the surface of the patients body by fluid pressure. A convenient construction is that shown in 3 in which a fabric casing 1' is shown of sufficient length to encircle an ordinary persons arm, and having a plurality of rows of hooks 3 between which lacings may be passed to bind the device in position. One or more extra rows of hooks 3 may be located on the casing to accommodate arms of different sizes. The rubber bag 4 within the cuff or bandage is preferably considerably shorter than the surrounding fabric casing, being adapted to bear only against a portion of the circumference of the patients arm corresponding to the location of the artery. We consider it advantageous to avoid encircling the patient s arm with the ex ansive vessel or membrane, since the app 'cation of the latter at points beyond the particular location of the artery is unnecessary and ainful. The bag 4. has a rubber or similar exible tube 2 extending therefrom and communicating with its interior.

In place of the pump and mercury tube apparatus hitherto generally used, we provide means for obtaining a water column, the height of which may be varied at will to any degree Within the ranges ordinarily measured. In a healthy adult human being, the average normal blood pressure amounts to about 100 to 145 mm. of mercury. This pressure is equivalent to that of a Water column between 4% and 6 1- feet in height. Abnormal blood pressures run considerably hi her and lower than this value, and it is evident that means must be employed for securing a corresponding range in the variable water column.

We provide a vessel, preferably a fabric covered rubber or similar ba 5, the most particular characteristic of wlnch is that it is very flexible or flaccid so as to exert substantially no pressure on its contents, except that transmitted from the atmosphere. To this bag, we connect a rubber or other tube 6,

which is joined to the tube 2, the whole tube.

having a com lete length eqlpal to the height of a water co umn giving t e greatest pressures to be measured. For this purpose, a length of 13 or 14 feet is ordinarlly amply sufficient. For ordinary cases, a lesser length would answer all requirements. The bag 5 constitutes a tank or reservoir for water, which fills the tubes 6 and- 2 and the bandage 1, and creates a watercolnnm'whmh transmits to said bandage a fluid pressure exactly proportionate to the hei ht of the water level in the bag 5 vertica y above sald bandage 1. This result occurs by reason of the aforesaid flexible character of the bag 5, which transmits atmospheric pressure to the surface of the water column as freely as if the latter were 0 en directly to the atmosphere. It is practica ly important in the use of the present invention that the pressure of the fluid column should only result from its own fluid height, without any additions or corrections on account of the air pressure above, and this can only be attained by insuring the application of atmospheric pressure to the top surface of the water column under allcircumstances. The form of vessel 5 shown,

- having very thin flexible walls, secures this result. The effective pressure of the water column is varied by adjusting the height of the bag 5, and is determined by observing the vertical length of the tube 6, which depends from the bag 5 to a point on a level with the bandage 1 or with the heart of the patient.

7 designates a fixture comprising a metal frame 8 havin a hooked portion 9 which may be engage upon the picture molding of a 130m or any other object of sufficient altitu e.

10 designates a socket fixed'to the frame 8 and adapted to receive the extremity of a cane or umbrella by means of which the fixture is conveniently raised and attached to the desired point. The frame 8 is deflected upwardly over the top of the pulley wheel 1 1, terminating in a rounded curved extremity 12. The form of this extension or extremity permits the insertion of a cord 13 on to the pulley, but acts as a guide to revent the cord accidentally leaving the pn ley when in of pressure.

use. The cord 13 has one end attached to the bag 5, and at its other end depends within reach of the operator who may by this means raise and lower the ba 5 to any altitude limited only by the heig t of the fixture 7 or the length of the rubber tube.

The tube 6 is graduated in equally-spaced divisions corresponding to unit increments A convenient unit standard is one millimeter of mercury, in which case each unit division on the tube 6 corresponds to the specific gravity of mercury in millimeters of lmeal extent. The zero of the scale is located at or near the middle of the bag 5, and from this point, the graduations extend in a continuous sequence throughout the tubes 6 and 2 to the cufl or bandage 1. In addition to these graduations, we distinguish different sections of the tube by different colors, or otherwise; for example, the upper art 6 may be colored blue, and the extreme ower part 2 red. Between these two colored portions, there may be a section 6 of white. It is obvious that the tube may be in one integral length throughout, but we prefer to have a detachable connection or 'oint 15 at some point therein, preferably etween the differently colored portions.

We have referred to the fact that the zero of the scale divisions should always be opposite the level of the fluid in the bag 5. Inasmuch as this level is likely to vary somewhat, depending on the amount of fluid supplied, together with the shape and character of the patient s arm and the tightness of the bandage, it is desirable to provide means by which such variation can be compensated for. For this purpose we make use of a tape or similar flexible element 16 fastened to the tube 6 at the point 17 and on which the scale divisions below, say 35 mm., are continued upward to the zero point where we fasten a loop or eye 18. 19 designates a plurality of hooks at different levels on the bag 5 to any one of which the eye 18 may be attached, dependin on the fluid level in the bag. The fluid leve in the bagcan be accurately noted by any medical practitioner by palpation, that is, by

gently tapping on its surface with the fingers.

It is possi le to tell the location of the fluid level very accurately by the character of the impact or. resistance when the finger strikes against a portion of the bag which is backed by fluid pressure and when backed by air pressure. The flexible tube 6 loops itself automatically at 20 to accommodate this adjustment. In this way the height of the fluid column is made to accurately correspond with the scale divisions.

The use and operation is as follows: The sections of the tube are se arated at the point 15, and theair sucke out of the res ective sections and bags. Water is then alowed to siphon into each section, and, when a sufficient quantity determined by the capacity of the bags, has been admitted, the tu e sections are joined under water. The bandage 1 is then a plied to the arm or other portion of the b0 y where convenient and the practitioner with one hand on the pulse of the patient gradually raises the bag 5 by pulling on the cord 13. As the elevation in-' creases the fluid pressure in the vessel 4 becomes greater and eventually pre onderates over the pressure of the blood. en such reponderance occurs the artery will be colapsed and restricted, and the practitioner is able to note this result by the patients pulse which grows weaker until finall it is 1m erceptible, at which oint the sea e will in icate at the level of t e arm or heart ihe pressure of the blood. The practitioner cansee at a glance whether the patients blood pressure is above or below normal by the color of the flexible tube at the reading point on the scale. if any portion of the blue section 6 is opposite the line of the heart or bandage, the patients blood is below normal pressure. If the red section is opposite, the patients blood pressure is above normal. If the white is opposite, the patients blood pressure is within normal limits. The numerical values are obtained by observing the scale divisions. In unusually high pressure cases, it is, of course, necessary to attach the i pulley to a staircase or some point where a suiiicient v altitude is available. By this means, it is possible to read with the greatest possible accuracy, the highest as well as the 1 lowest pressure cases, which has not hitherto been possible in air mercury machines. In the use of the apparatus, it is important to I see that the air is absolutely excluded from i l the tubes before a test is made, since the presence of bubbles vitiates the accuracy of Q the readings. With this simple precaution, i the method is susceptible of as great accul racy as the nature of this character of a test will permit.

What we claim, is:

1. A sphygmomanometer comprising a bandage adapted to be a lied to the arm or body of a patient, a rulilier bag contained therein and having a rubber tube extension, a vessel at the terminal end of said rubber tube extension, means adapted to be at- 1 tached to an elevated support for raising said vessel to any required height above the rubj ,toa

tension, means for lacing said ass her bag corresponding to awater column balancing the blood pressure of the patient, and. measuring means associated with said rubber tube for determining the length of the portion thereof which depends from said vessel point horizontally opposite the location of said bandage.

2. A sphygmomanometer comprising a bandage adapted to be applied to the arm or body of a patient, a rubber bag contained in said bandage and having a flexible tube exbandage on the patient, a second bag at the terminal end of said flexible tube, means adapted to be attached to an elevated support for raising T said second bag to a height above the first bag corresponding to a water column balancing the blood pressure of the patient, a connection or joint in water, means including an element 16 and books 19 for varying the relation of said second bag to said divisions, whereby the level of water in said second bag may be compensated for, and measuring means associated with said tube for determining the length of the portion thereof which depends from said second bag to a point horizontally opposite the location of said bandage.

In witness whereof, we subscribe our sign a tu res, in the presence of two witnesses.

LOUIS F. BISHOP. RALPH. GRAO t. Witnesses A. W. MEAD, IDA RUTHERFORD.

said tube whereby it may be separated to fill the apparatus with 

